This invention relates to a sheet winch of the general type employed in a marine environment to provide a mechanical advantage in the hauling of ropes or lines in which the forces required are substantial, particularly in large sail boats. In addition to facilitating hauling of the lines by the mechanical advantage achieved, it often is important that the winch be operated as fast as possible, especially when racing such boats, where the handling of the sails as quickly as possible often is a determinative factor in the outcome of the race. In general, the requirements of providing the desired mechanical advantage and winding speed are inconsistent with each other because one must be achieved at the expense of the other. Typically, the prior multiple speed winches have employed two gear transmission ratios between the drive shaft and drum and the selection of the desired gear ratio depends on whether the winch handle (and shaft) are rotated in one direction or the other.
In some instances during the sailing of a boat, the mechanical advantage obtainable by the lowest gear ratio is less than is actually needed and it would be desirable to be able to employ a third, higher winding speed for the drum than that which can be achieved with either of the two gear transmission ratios. To this end, winches have been proposed which provide a direct drive (1:1 ratio) so that the drum can be rotated at the same angular speed as the winch handle itself.
Various devices have been proposed for achieving the direct drive. One such device has a rotatable ring at the top of the winch drum which must be manually rotated in order to effect the direct drive engagement. This type of winch can be dangerous in that the winch operator must place his fingers in the path of the rotating winch handle in order to shift the device to engage or disengage the direct drive ratio. Also, because with this device the operator must necessarily operate the winch handle with only one hand while shifting the ring, the operation of the winch is somewhat interrupted, or at least is erratic.
In another type of proposed direct drive winch, a detent is pivoted to and extends upwardly from the top of the winch drum so that it can be engaged by the winch handle. This device also requires the operator to manipulate the detent, in the path of the winch handle, and also requires him, at least for a short time period, to operate the winch handle with only one hand.
It is also desirable to employ a construction in such sheet winches in which the gearing is easily and readily accessible for maintenance, inspection or replacement. In addition, it also is desirable for such sheet winches to wear uniformly and, to that end, the construction of the rotatable mounting and bearing arrangement for the shaft and drum is an important constructional feature in such winches. It is among these objects of the invention to provide an improved sheet winch construction which achieves these objects and also provides an improved arrangement for obtaining a direct drive ratio between the winch handle and the winch drum.